Digital focus and tracking servo system with multi-zone calibration
View Patent ↗A multi-zone calibration system is disclosed. The multi-zone calibration system calibrates the operating parameters of an optical disk drive over a plurality of zones over an optical media. The optical media, in addition, can have writeable and premastered portions. The operating parameters can be calibrated for each of the media types in each of the zones. Additionally, the operating parameters can be calibrated for each type of operation (e.g., read or write) in each zone.
1. A method of calibrating operating parameters in an optical disk drive over a plurality of zones, the optical disk drive including a plurality of photodetectors producing a corresponding plurality of photodetector signals, wherein the optical disk drive includes a plurality of amplifiers corresponding to the plurality of photodetector signals such that each photodetector signal is individually gain-adjusted by its corresponding amplifier, the plurality of amplifiers thereby producing a plurality of gain-adjusted photodetector signals, the method comprising:
providing a digital signal processor configured to receive digitized versions of the gain-adjusted photodetector signals and form a focusing error signal (FES) and a tracking error signal (TES) from the digitized versions, the digital signal processor configured with servo algorithms that process TES and FES to adjust focus and tracking in the optical disk drive;
positioning the optical pick-up unit over a current zone, the current zone being one of the plurality of zones in an optical media;
performing calibration algorithms to optimize a gain value for each of the amplifiers with respect to the current zone; and
proceeding to a next zone, the next zone being another one of the plurality of zones, unless all of the plurality of zones have been calibrated.
2. The method of claim 1 , wherein performing the calibration algorithms includes performing a tracking error signal offset calibration.
3. The method of claim 1 , wherein performing the calibration algorithms includes performing a tracking error signal gain calibration.
4. The method of claim 1 , wherein performing the calibration algorithms includes performing a non-linearity calibration.
5. The method of claim 1 , wherein performing the calibration algorithms includes performing a notch filter calibration.
6. The method of claim 1 , wherein performing the calibration algorithms includes performing a loop gain calibration.
7. The method of claim 1 , wherein performing the calibration algorithms includes performing a tracking error signal to focus error signal cross coupling calibration.
8. The method of claim 1 , wherein the plurality of zones includes a first zone having a writable portion and a second zone having a premastered portion.
9. An optical disk drive, comprising: an optical pick-up unit including a plurality of photodetectors; a plurality of amplifiers corresponding to the plurality of photodetectors such that each amplifier amplifies a photodetector output signal from the corresponding photodetector; an analog-to-digital converter coupled to receive signals from the amplifiers and digitize the received signals to provide digitized detector signals; at least one processor coupled to receive the digitized detector signals and form a focusing error signal (FES) and a tracking error signal (TES) from the digitized detector signals, the processor configured with servo algorithms that process TES and FES to calculate control signals to adjust focus and tracking in the optical disk drive; and a driver coupled to control a position of the optical pick-up unit in response to the control signals, wherein the at least one processor executes an algorithm that calibrates operating parameters over a plurality of zones by positioning the optical pick-up unit over a current zone, the current zone being one of the plurality of zones on an optical media, performing calibration algorithms to optimize a gain value for each of the amplifiers with respect to the current zone, and proceeding to a next zone, the next zone being another one of the plurality of zones, unless all of the plurality of zones have been calibrated.
10. The drive of claim 9 , wherein the at least one processor further executes an algorithm that calibrates the operating parameters over a plurality of media types within each of the plurality of zones.
11. The drive of claim 9 , wherein the at least one processor further executes an algorithm that calibrates the operating parameters over a plurality of operating conditions over at least one of the plurality of media types.